In a conventional MIS transistor, as shown in FIG. 2, a gate insulating film 25 and a gate electrode 26 are formed on a semiconductor substrate 21 successively in a mentioned order, and a source 23 and a drain 24 are formed by ion implantation.
In order to cause the above described phenomenon in the MOS transistor having the conventional structure, the channel length L must be small and the operating voltage must be high (V.sub.D .gtoreq.10 V) as reported, for example, in IEEE, EDL-8, No. 7, July, 1987.
Accordingly, as long as it is used at an ordinary power supply voltage (5 V or lower), the MIS transistor having the conventional structure can realize only such a limited current driving capability that is dependent on the power supply voltage V, device size W/L, carrier mobility .mu., etc.
An object of the present invention is to enable the phenomenon, which occurs only when the channel is short and the power supply voltage is high in the prior art, to occur even when the power supply voltage is low and the channel is long.